A lithium-ion secondary battery has been widely used as a power source of, e.g., a notebook-sized personal computer, a video camera, a cellular phone, or an electric automobile. As such a lithium-ion secondary battery, a battery in which a periphery of a battery body is covered with a case has been used. As the packaging material for cases, for example, a packaging material in which an outer layer made of an oriented polyamide film, an aluminum foil layer, and an inner layer made of a non-oriented polypropylene film are integrally bonded in this order is known (see Patent Document 1).
In such a packaging material for battery cases, since the packaging material is formed into various battery configurations, it is required to have high deep drawing formability. In order to give high deep drawing formability, conventionally, a packaging material in which fatty acid amide series slip characteristics imparting components are coated on a surface of an outer layer film to enhance the slipping of the material in a die at the time of forming (see Patent Document 2) or a packaging material comprising an aluminum foil layer and an outer layer film thicker than the aluminum foil layer have been employed.
Patent Document 1: JP 2001-6631, A
Patent Document 2: JP 2002-216714, A